Rhodium(III) complexes derived from complexation of metal with azomethine linkage of chitosan biopolymer Schiff base ligand: Spectral, thermal, crystalline, morphological and electrochemical studies

3.4. Cyclicvoltammetery Cyclic voltametry is a conversant electro analytical technique for the study of electro active element. Researchers have applied this technique to the study of redox property of electrochemically active specis. [25] The reduction/oxidation system remains in equilibrium all through around the electrochemical reaction was said to be irreversible/quasi-reversible. This was ascribed to electron transfer on the metal complexes. In rhodium(III) complexes, the metal form wide range of octahedral complexes when the metal ion has complexed with nitrogen and oxygen in the Schiff base ligands. The octahedral struture of rhodium complexes was exhibited +3 oxidation state. The Rh(III) complexes were invariably prepared and it was proclaimed some form of reduction property, either of similar Rh(III) complexes with azomethine linkage which behaves as complexing agent. As noted under rhodium complexes, it was derived from amine and aldehyde which has furnished by O or N atoms with specific circumentences. Furthermore, the reduction process was carried out by the presence of metal which was complexed usually with halogens, water and amine ligands. Also, the metal-ligand complexation can be carried out by hydridic species of π-bonding ligands which results the formation of M(III) complexes. [26] The study of the electrochemical behavior of all Rhodium(III) complexes in suitable organic solvent were carried out in the potential range of -1.1 V to -1.1 V. The redox waves are mainly attributed to the metal centre as RhIV- RhIII and RhIII – RhII couple and complexes have shown peak-to-peak seperation value (ΔEp) in the constant poential ranges. The rhodium(III) complexes were exhibited both reversible oxidation and irreversible reduction peaks. [27] In the cyclic voltammogram of rhodium(III) complex, the [Rh(Chi4Hy3mb)(H2O)2]Cl2 complex was showed the cathodic and anodic peaks which is illustrated in Fig.6(a). This complex has derived from the ligand containing electron withdrawing group (-OCH3).[28] The clear cathodic peak (reduction) was occured in the negative range at -1.1V with a peak current of iρc is -0.5V. This indicate that a definite cathodic process was take place at this potential. In the reverse scan, the anodic oxidative process was found to occur at 1.9V with a peak current of iρa 800mμ. The other complexes such as [Rh(Chi2Hymb)(H2O)2]Cl2 and [Rh(Chi2Hy3mb)(H2O)2]Cl2 (Fig.6(b, c)) showed their reduction potentials in negative range of -1.3V with corresponding cathodic peaks -0.25mV and -0.16V respectively. Oxidation potential of both complexes was found to occur at 1.97V with peak current of iρa 450μ